Magnets and springs are widely used in a door open/close devices for cabinets for audio systems and other cabinets. Such devices comprise a movable body with a magnet attached to one end thereof which is engaged when pushed and returns to the initial position when further pushed to release the engagement, and includes an attractable piece to be attracted by said magnet, the movable body and the attractable piece being respectively attached to the main body of a box and a door. When a door of such a cabinet is pushed toward the main body, a free end of said door projects to push away the main body and when the door is pulled outward by a hand, the magnetic engagement between the piece and the magnet is released to fully open the door. Alternatively, the door is pushed open by the movable body.
However, the door closing device of the above type is structured to prevent the door from opening by vibration or slight impact. As the door often stops in the state magnetically attracted to the movable body even if the free end of the door is projected (opened), it is necessary to open it further by hand. In the latter type of the above mentioned device, the movable body has to keep enough projecting (opening) force to thrust open the door by inertia. In the case where the door is made of acrylic material or thin glass, or an opening of the cabinet is small, or of a double-leaf door, as the door has small intertia, an intense or sharp pushing force is required. However, if the pushing force is increased, it would give an unpleasant sound. Furthermore, vibration in the cabinet caused by pushing is disadvantageous since the needle may skip to damage the disc when being played or it may damage the audio system. If a larger-sized open/close device is required to withstand such vibration, it may lead to a higher cost.
There has been proposed a device which enables a door to open with smaller force on a movable body by making yokes on both sides of a magnet to project in the direction of the door to thereby reduce the magnetic lines of force. However, in such a device, it is required to slide the yokes against the attracting force of the magnet, which requires a larger device and thus leads to a higher cost. In another device comprising a cylindrical magnet and an arc yoke along the outer peripheral of said magnet, the magnet force of the yoke is reduced by turning the yoke to a neutral position. However, disadvantages such as a higher cost of the device as in the former type due to the friction resistance at the time of turning are also noted in this device.
As shown in FIGS. 15 through 17, prior art magnet catchers are shown having a movable body (101) which has a magnet attaching hole (103) open to both sides and a slit (106) on the front end thereof from which only the front end of a yoke (105) projects, the yoke being attached to a magnet (104) which is mounted in said magnet attaching hole (103), and an endless guide channel (108) is provided on the rear upper surface to receive a bent end (107a) of an engaging pin (107) which connects the movable body (101) and a case (102). A recess channel (110) is provided on the rear lower surface for receiving a coil spring (109). A fitting part (111) extending on both sides for fixing the case is projectedly installed on the case (102), in the rear end of which a through-hole (112) for said pin (107) is bored. A flanged projection (113) is provided to engage with the bent end (107b) of the pin (107). The projection (113) has U-shaped channel (114) adjacent to the through-hole (112) to correspond thereto. On the bottom of the channel (114) is bored a hole (115) to which the end (107b) of the pin (107) is inserted.
Therefore, in integral molding of a movable body (101) with synthetic resin, it is necessary to use a mold with five parts movable in the directions indicated as shown (by the arrows X--X), in FIGS. 16 and 17, which is open in the top, bottom, left, right and the front. That results in a higher cost and a troublesome manufacturing process which may sometimes yield defective products.